From a818830babc690b86dae04a15b63f66f63a0eb45 Mon Sep 17 00:00:00 2001
From: tycho garen <garen@tychoish.com>
Date: Wed, 16 Mar 2022 10:24:41 -0400
Subject: [PATCH] libs/clist: remove unused surface area

---
 internal/libs/clist/bench_test.go |  2 +-
 internal/libs/clist/clist.go      | 58 +++++++------------------------
 internal/libs/clist/clist_test.go |  2 +-
 3 files changed, 14 insertions(+), 48 deletions(-)

diff --git a/internal/libs/clist/bench_test.go b/internal/libs/clist/bench_test.go
index 95973cc76..ee5d836a7 100644
--- a/internal/libs/clist/bench_test.go
+++ b/internal/libs/clist/bench_test.go
@@ -12,7 +12,7 @@ func BenchmarkDetaching(b *testing.B) {
 	b.ResetTimer()
 	for i := 0; i < b.N; i++ {
 		start.removed = true
-		start.DetachNext()
+		start.detachNext()
 		start.DetachPrev()
 		tmp := nxt
 		nxt = nxt.Next()
diff --git a/internal/libs/clist/clist.go b/internal/libs/clist/clist.go
index 99e5f05bf..fbe4eccae 100644
--- a/internal/libs/clist/clist.go
+++ b/internal/libs/clist/clist.go
@@ -72,27 +72,9 @@ func (e *CElement) NextWait() *CElement {
 	}
 }
 
-// Blocking implementation of Prev().
-// May return nil iff CElement was head and got removed.
-func (e *CElement) PrevWait() *CElement {
-	for {
-		e.mtx.RLock()
-		prev := e.prev
-		removed := e.removed
-		signal := e.prevWaitCh
-		e.mtx.RUnlock()
-
-		if prev != nil || removed {
-			return prev
-		}
-
-		<-signal
-	}
-}
-
-// PrevWaitChan can be used to wait until Prev becomes not nil. Once it does,
+// prevWaitChan can be used to wait until Prev becomes not nil. Once it does,
 // channel will be closed.
-func (e *CElement) PrevWaitChan() <-chan struct{} {
+func (e *CElement) prevWaitChan() <-chan struct{} {
 	e.mtx.RLock()
 	defer e.mtx.RUnlock()
 
@@ -131,7 +113,7 @@ func (e *CElement) Removed() bool {
 	return isRemoved
 }
 
-func (e *CElement) DetachNext() {
+func (e *CElement) detachNext() {
 	e.mtx.Lock()
 	if !e.removed {
 		e.mtx.Unlock()
@@ -153,7 +135,7 @@ func (e *CElement) DetachPrev() {
 
 // NOTE: This function needs to be safe for
 // concurrent goroutines waiting on nextWg.
-func (e *CElement) SetNext(newNext *CElement) {
+func (e *CElement) setNext(newNext *CElement) {
 	e.mtx.Lock()
 
 	oldNext := e.next
@@ -174,7 +156,7 @@ func (e *CElement) SetNext(newNext *CElement) {
 
 // NOTE: This function needs to be safe for
 // concurrent goroutines waiting on prevWg
-func (e *CElement) SetPrev(newPrev *CElement) {
+func (e *CElement) setPrev(newPrev *CElement) {
 	e.mtx.Lock()
 	defer e.mtx.Unlock()
 
@@ -188,7 +170,7 @@ func (e *CElement) SetPrev(newPrev *CElement) {
 	}
 }
 
-func (e *CElement) SetRemoved() {
+func (e *CElement) setRemoved() {
 	e.mtx.Lock()
 	defer e.mtx.Unlock()
 
@@ -250,7 +232,7 @@ func (l *CList) Front() *CElement {
 	return head
 }
 
-func (l *CList) FrontWait() *CElement {
+func (l *CList) frontWait() *CElement {
 	// Loop until the head is non-nil else wait and try again
 	for {
 		l.mtx.RLock()
@@ -273,22 +255,6 @@ func (l *CList) Back() *CElement {
 	return back
 }
 
-func (l *CList) BackWait() *CElement {
-	for {
-		l.mtx.RLock()
-		tail := l.tail
-		wg := l.wg
-		l.mtx.RUnlock()
-
-		if tail != nil {
-			return tail
-		}
-		wg.Wait()
-		// l.tail doesn't necessarily exist here.
-		// That's why we need to continue a for-loop.
-	}
-}
-
 // WaitChan can be used to wait until Front or Back becomes not nil. Once it
 // does, channel will be closed.
 func (l *CList) WaitChan() <-chan struct{} {
@@ -326,8 +292,8 @@ func (l *CList) PushBack(v interface{}) *CElement {
 		l.head = e
 		l.tail = e
 	} else {
-		e.SetPrev(l.tail) // We must init e first.
-		l.tail.SetNext(e) // This will make e accessible.
+		e.setPrev(l.tail) // We must init e first.
+		l.tail.setNext(e) // This will make e accessible.
 		l.tail = e        // Update the list.
 	}
 	l.mtx.Unlock()
@@ -365,16 +331,16 @@ func (l *CList) Remove(e *CElement) interface{} {
 	if prev == nil {
 		l.head = next
 	} else {
-		prev.SetNext(next)
+		prev.setNext(next)
 	}
 	if next == nil {
 		l.tail = prev
 	} else {
-		next.SetPrev(prev)
+		next.setPrev(prev)
 	}
 
 	// Set .Done() on e, otherwise waiters will wait forever.
-	e.SetRemoved()
+	e.setRemoved()
 
 	return e.Value
 }
diff --git a/internal/libs/clist/clist_test.go b/internal/libs/clist/clist_test.go
index a0482fc40..c7c8ce535 100644
--- a/internal/libs/clist/clist_test.go
+++ b/internal/libs/clist/clist_test.go
@@ -320,7 +320,7 @@ FOR_LOOP:
 FOR_LOOP2:
 	for {
 		select {
-		case <-prev.PrevWaitChan():
+		case <-prev.prevWaitChan():
 			prev = prev.Prev()
 			seen++
 			if prev == nil {